Tactile feedback technology provides touch screen users with the "sensation" that they are actually depressing traditional mechanical buttons.
The tactile feedback effect is created when the user simultaneously sees a video button depress, hears an audio file of the mechanical "click" and feels a vibration in the touch screen's glass surface. The user instinctively interprets the combination of these three sensations as depressing a mechanical button, when actually they're touching a solid glass surface.
Product implementations:
How Tactile Feedback Technology Works (PDF 106KB)